Techniques to determine the thickness of metal-containing films can include using eddy current mapping. For example, a coil having an alternating current running through the coil can be brought into proximity with a metal-containing film. In response to a first magnetic field caused by the alternating current flowing through the coil, an opposing second magnetic field will be generated in the metal-containing film. The second magnetic field may be caused by an induced current, e.g., an eddy current, flowing along the metal-containing film. In embodiments where the metal-containing film may be about 1000 angstroms in thickness or greater, the aforementioned eddy current mapping technique can accurately measure the thickness of the metal-containing film. However, applying this technique to measure metal-containing films having thicknesses below about 500 angstroms, for example such as on the scale of hundreds or tens of angstroms requires high frequencies, such as in the gigahertz (GHz) range to completely eliminate measurement errors related to contributions from underlayer properties, such as current loops and doping.
Accordingly, methods and apparatus for determining parameters in metal-containing films, such as film thickness, are provided herein.